In-cell touch panel device and method for controlling in-cell touch panel

ABSTRACT

A control circuit of an in-cell touch panel device associates a touch position P1 and a touch position P2 with each other when a refresh rate is F1 and a touch-to-touch distance d1 between the successive touch positions P1 and P2 is equal to or less than a determination distance D1. The control circuit associates a touch position P3 and a touch position P4 with each other when a touch-to-touch distance d2 between the touch position P3 detected last in a period in which the refresh rate is F2 lower than F1 and the touch position P4 detected first since a period in which the refresh rate is F1 starts is equal to or less than a determination distance D2 greater than the determination distance D1.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese PatentApplication Number 2021-164814 filed on Oct. 6, 2021. The entirecontents of the above-identified application are hereby incorporated byreference.

BACKGROUND TECHNICAL FIELD

The disclosure relates to an in-cell touch panel device and a method forcontrolling an in-cell touch panel.

Typically, a touch panel device that detects a touch position of afinger is known. Such a touch panel device is disclosed in, for example,JP 6012437 B.

The touch panel device in JP 6012437 B described above includes a mutualcapacitive touch panel, a touch panel controller that controls the touchpanel, and a subprocessor. The subprocessor switches the touch paneldevice between a sleep state where touch detection by the touch panel isnot performed, and an active state where the touch detection by thetouch panel is performed. Further, the subprocessor periodicallyswitches the touch panel device to the active state after the touchpanel device enters the sleep state. In this way, the touch detectioncan be periodically performed while reducing power consumption ascompared to a case where the touch panel device is always in the activestate.

Further, typically, an in-cell touch panel device including an in-celltouch panel that performs both of display of an image and detection of atouch position is known. Such an in-cell touch panel determines that twosuccessive touches are those by the same pointer when a distance betweentwo successive touch positions is equal to or less than a predetermineddetermination distance.

SUMMARY

Here, also in the in-cell touch panel, it is conceivable that processingof reducing a refresh rate of display of an image (processing of settingto a sleep state) can be performed in order to reduce power consumptionwhen the in-cell touch panel is not touched within a predeterminedperiod.

However, since the display of an image and the touch detection areperformed in a time division manner in the in-cell touch panel, a reportrate of the touch detection (a cycle of performing the touch detection)needs to match the refresh rate of the display of an image. Thus, whenthe refresh rate decreases, the report rate of the touch detection alsodecreases. As a result, in a case where the refresh rate is changed froma low state to a high state while a pointer is moving and touching thein-cell touch panel, immediately after the change, a touch positiondetected in a state where the refresh rate is low (a state where a cycleof the touch detection is long) is detected as a position away from thecurrently detected touch position. In this way, there is a problem thata distance between the two successive touch positions is greater thanthe predetermined determination distance, and the currently detectedtouch position is mistakenly determined to be the position of a touch bya pointer different from the pointer having previously touched thein-cell touch panel.

Thus, the disclosure is made in order to solve the problem describedabove, and an object thereof is to provide an in-cell touch panel deviceand a method for controlling an in-cell touch panel that allowappropriate detection of successive touches even before and after achange of a refresh rate from a low state to a high state.

In order to solve the problem described above, an in-cell touch paneldevice according to a first aspect of the disclosure includes: anin-cell touch panel configured to perform display of an image anddetection of a touch position in a time division manner; and a controlcircuit configured to control the in-cell touch panel, in which thecontrol circuit is configured to change a refresh rate of the in-celltouch panel between a first rate and a second rate lower than the firstrate, and the control circuit is further configured to cause the in-celltouch panel to perform detection of a touch position in a first cyclewhen the refresh rate is the first rate, cause the in-cell touch panelto perform detection of a touch position in a second cycle being a cyclelonger than the first cycle at the end at least within one frame period,when the refresh rate is the second rate, associate a first touchposition and a second touch position with each other when atouch-to-touch distance between the first touch position and the secondtouch position is equal to or less than a first determination distance,the first touch position and the second touch position beingsuccessively detected in a period in which the in-cell touch panel iscaused to perform detection of a touch position in the first cycle, andassociate a third touch position and a fourth touch position with eachother when a touch-to-touch distance between the third touch positionand the fourth touch position is equal to or less than a seconddetermination distance greater than the first determination distance,the third touch position being detected last in a period in which therefresh rate is the second rate and the fourth touch position beingdetected first since a period in which the refresh rate is the firstrate starts, when the refresh rate is changed from the second rate tothe first rate.

Further, a method for controlling an in-cell touch panel according to asecond aspect is a method for controlling an in-cell touch panelconfigured to perform display of an image and detection of a touchposition in a time division manner, and includes: changing a refreshrate of the in-cell touch panel between a first rate and a second ratelower than the first rate; causing the in-cell touch panel to performdetection of a touch position in a first cycle when the refresh rate isthe first rate; causing the in-cell touch panel to perform detection ofa touch position in a second cycle being a cycle longer than the firstcycle at the end at least within one frame period, when the refresh rateis the second rate; associating a first touch position and a secondtouch position with each other when a touch-to-touch distance betweenthe first touch position and the second touch position is equal to orless than a first determination distance, the first touch position andthe second touch position being successively detected in a period inwhich the in-cell touch panel is caused to perform detection of a touchposition in the first cycle; and associating a third touch position anda fourth touch position with each other when a touch-to-touch distancebetween the third touch position and the fourth touch position is equalto or less than a second determination distance greater than the firstdetermination distance, the third touch position being detected last ina period in which the refresh rate is the second rate and the fourthtouch position being detected first since a period in which the refreshrate is the first rate starts, when the refresh rate is changed from thesecond rate to the first rate.

The in-cell touch panel device having the configuration described aboveand the method for controlling an in-cell touch panel allow appropriatedetection of successive touches even before and after a change of arefresh rate from a second rate to a first rate higher than the secondrate.

BRIEF DESCRIPTION OF DRAWINGS

The disclosure will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a block diagram illustrating a configuration of an in-celltouch panel device 100 according to an embodiment.

FIG. 2 is a schematic view for describing a connection relationshipbetween an in-cell touch panel 1 and a control device 2.

FIG. 3 is a functional block diagram of a drive circuit 12.

FIG. 4 is a diagram for describing a connection relationship between aplurality of thin film transistors 14 and a plurality of pixelelectrodes 15, and the drive circuit 12.

FIG. 5 is a diagram for describing a relationship between a period DPfor displaying an image and a period TP for performing detection of atouch position.

FIG. 6A is a diagram schematically illustrating a state where a pointertouches the in-cell touch panel 1.

FIG. 6B is a diagram for describing a first example of provision ofidentification information.

FIG. 6C is a diagram illustrating a first example of display on thein-cell touch panel 1.

FIG. 7A is a diagram schematically illustrating a state where twopointers touch the in-cell touch panel 1.

FIG. 7B is a diagram for describing a second example of provision ofidentification information.

FIG. 7C is a diagram illustrating a second example of display on thein-cell touch panel 1.

FIG. 8A is a diagram illustrating a waveform of a signal INT and awaveform of a rate change notification signal RS when a refresh rate Fis changed from F2 to F1.

FIG. 8B is a diagram illustrating an example of display of the in-celltouch panel 1 when the refresh rate F is changed from F2 to F1.

FIG. 9A is a diagram for describing an operation of an in-cell touchpanel device 200 according to a comparative example.

FIG. 9B is a diagram illustrating an example displayed on an in-celltouch panel 201 of the in-cell touch panel device 200 according to thecomparative example.

FIG. 10 is a flowchart for describing control processing of a controlcircuit 20 according to an embodiment.

FIG. 11 is a diagram for describing a configuration of an in-cell touchpanel device 300 according to a modified example of an embodiment.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the disclosure will be described in detailwith reference to the drawings. In the drawings, the same orcorresponding portions are denoted by the same reference signs, and thedescription thereof will not be repeated. Note that, for ease ofdescription, in the drawings referred to below, configurations may besimplified or schematically illustrated, and some components may beomitted. Further, dimensional ratios between components illustrated inthe drawings are not necessarily indicative of actual dimensionalratios.

Configuration of In-Cell Touch Panel Device

A configuration of an in-cell touch panel device 100 according to thepresent embodiment will be described. FIG. 1 is a block diagramillustrating the configuration of the in-cell touch panel device 100according to the present embodiment. FIG. 2 is a schematic view fordescribing a connection relationship between an in-cell touch panel 1and a control device 2.

As illustrated in FIG. 1 , the in-cell touch panel device 100 includesthe in-cell touch panel 1 and the control device 2. The in-cell touchpanel device 100 is a display device having a touch detection function.For example, the in-cell touch panel device 100 is disposed in asmartphone, a tablet terminal, a personal computer, and the like. Asillustrated in FIG. 2 , the in-cell touch panel 1 and the control device2 are connected to each other via a flexible printed circuit board 3.

Configuration of In-Cell Touch Panel

The in-cell touch panel 1 detects coordinates (hereinafter referred toas a “touch position”) of a position touched by a pointer such as afinger and a pen, and also displays a video or an image. The in-celltouch panel 1 is, for example, a self-capacitive touch panel.

As illustrated in FIG. 2 , the in-cell touch panel 1 includes aplurality of touch detection electrodes 11, a plurality of drivecircuits 12, and a plurality of touch detection lines 13. The pluralityof touch detection electrodes 11 are disposed in matrix, for example.Then, each of the plurality of touch detection electrodes 11 isconnected to any one of the plurality of drive circuits 12 via the touchdetection line 13.

FIG. 3 is a functional block diagram of the drive circuit 12. The drivecircuit 12 includes a touch detection electrode drive unit 12 a, a gatedrive unit 12 b, and a source drive unit 12 c. The touch detectionelectrode drive unit 12a of the drive circuit 12 supplies a drive signalto the touch detection electrode 11. The drive signal has a waveformchanging according to a capacitance between a pointer and the touchdetection electrode 11. The touch detection electrode drive unit 12aacquires a detection signal being the drive signal having the changedwaveform from the touch detection electrode 11, and detects a touchposition by the pointer, based on the detection signal. The touchdetection electrode drive unit 12a outputs the touch position to thecontrol device 2 (see FIG. 2 ). Note that, in FIG. 3 , the touchdetection electrode drive unit 12 a, the gate drive unit 12 b, and thesource drive unit 12 c are described as functional blocks in the drivecircuit 12, but the touch detection electrode drive unit 12 a, the gatedrive unit 12 b, and the source drive unit 12 c may be formed inseparate integrated circuits.

FIG. 4 is a diagram for describing a connection relationship between aplurality of thin film transistors 14 and a plurality of pixelelectrodes 15, and the drive circuit 12. As illustrated in FIG. 4 , thein-cell touch panel 1 includes the plurality of thin film transistors 14and the plurality of pixel electrodes 15. The gate drive unit 12 b isconnected to a gate line 16. The source drive unit 12 c of the drivecircuit 12 is connected to a source line 17. A gate electrode of thethin film transistor 14 is connected to the gate line 16, and a sourceelectrode of the thin film transistor 14 is connected to the source line17. Further, a drain electrode of the thin film transistor 14 isconnected to the pixel electrode 15. Further, the pixel electrode 15forms an electrostatic capacitance with the touch detection electrode11. The touch detection electrode 11 is a common electrode commonlyprovided to the plurality of pixel electrodes 15.

The gate drive unit 12 b of the drive circuit 12 sequentially supplies agate signal (scanning signal) to each of the plurality of gate lines 16in a period DP (see FIG. 5 ) for displaying an image described below.Further, the source drive unit 12 c of the drive circuit 12 supplies asource signal based on an image signal to each of the plurality ofsource lines 17. In this way, when the thin film transistor 14 suppliedwith the gate signal is turned on the source signal is written in thepixel electrode 15. Then, in the in-cell touch panel 1, an electricalfield generated by the pixel electrode 15 and the touch detectionelectrode 11 (common electrode) drives a liquid crystal layer (notillustrated) to display an image.

Configuration of Control Device

The control device 2 is a device that controls the in-cell touch panel1. As illustrated in FIG. 1 , the control device 2 includes a controlcircuit 20 including a timing controller 21 and a touch panel controller22, a host controller 23, and a storage unit 24. The control circuit 20and the host controller 23 are connected by, for example, an I²C bus;this configuration makes it possible to perform serial communicationtherebetween. The storage unit 24 is a read only memory (ROM) or anon-volatile memory such as a flash memory, for example, and stores aprogram 24 a.

FIG. 5 is a diagram for describing a relationship between the period DPfor displaying an image and a period TP for performing detection of atouch position. By transmitting a timing signal to the touch panelcontroller 22 in a regular cycle, the timing controller 21 causes thetouch panel controller 22 to perform display of an image on the in-celltouch panel 1 and detection of a touch position by the in-cell touchpanel 1 in a time division manner. As illustrated in FIG. 5 , the timingcontroller 21 transmits the timing signal to the touch panel controller22 such that the period DP for displaying an image on the in-cell touchpanel 1 and the period TP for detecting a touch position by the in-celltouch panel 1 alternate. The timing controller 21 makes the period DPand the period TP repeat a plurality of times per one frame period.

As illustrated in FIG. 2 , the touch panel controller 22 is connected tothe plurality of drive circuits 12. The touch panel controller 22controls detection of a touch position on the in-cell touch panel 1 viathe touch detection electrode drive unit 12a of each of the plurality ofdrive circuits 12. For example, as illustrated in FIG. 5 , the touchpanel controller 22 supplies the drive signal to some of the pluralityof touch detection electrodes 11 of the in-cell touch panel 1 in theperiod TP. Further, the touch panel controller 22 receives the detectionsignal from the touch detection electrode 11 supplied with the drivesignal. Then, the touch panel controller 22 performs supply of the drivesignal and reception of the detection signal for each period TP, andprocesses the detection signals (magnitude of a capacitance) such thatMAP-like data is configured, after receiving the detection signal fromall of the touch detection electrodes 11. Then, the touch panelcontroller 22 performs processing such as calculation of the center ofgravity from the MAP-like data, and generates a touch coordinate reportincluding information about coordinates (touch position) of a positiontouched by a pointer. Then, the touch panel controller 22 transmits thetouch coordinate report to the host controller 23. Further, the touchpanel controller 22 transmits, to the host controller 23, a signal INTindicating that generation of the touch coordinate report is completed.For example, as illustrated in FIG. 5 , the touch panel controller 22switches a level of the signal INT from a state of “High” to a state of“Low” when generation of the touch coordinate report is completed. Inthe example illustrated in FIG. 5 , the touch panel controller 22transmits the touch coordinate report to the host controller 23 twiceper one frame period, but the disclosure is not limited to twice, andmay be once, or three or more times.

FIG. 6A is a diagram schematically illustrating a state where a pointertouches the in-cell touch panel 1. FIG. 6B is a diagram for describing afirst example of provision of identification information. FIG. 6C is adiagram illustrating a first example of display on the in-cell touchpanel 1. When the pointer moves while touching the in-cell touch panel 1as illustrated in FIG. 6A, the touch panel controller 22 providesidentification information (hereinafter referred to as “ID”) to each ofa plurality of detected touch positions as illustrated in FIG. 6B. Here,as illustrated in FIG. 6C, when a refresh rate F of the in-cell touchpanel 1 is F1 (first rate), the touch panel controller 22 compares atouch-to-touch distance d1 being a distance between two successive touchpositions P1 and P2 with a determination distance D1. Then, when thetouch-to-touch distance d1 between the two successive touch positions P1and P2 is equal to or less than the determination distance D1, the touchpanel controller 22 provides the same ID to the two successive touchpositions P1 and P2. In the example in FIG. 6B, the same “ID1” isprovided to all touch positions. Then, the touch coordinate reportincludes the touch positions provided with the IDs.

FIG. 7A is a diagram schematically illustrating a state where twopointers touch the in-cell touch panel 1. FIG. 7B is a diagram fordescribing a second example of provision of ID. FIG. 7C is a diagramillustrating a second example of display on the in-cell touch panel 1.When the two pointers (for example, two fingers) sequentially touch aportion on a left side and a portion on a right side of the in-celltouch panel 1, respectively, as illustrated in FIG. 7A, the touch panelcontroller 22 provides ID to each of a plurality of detected touchpositions P1 a and P2 a as illustrated in FIG. 7B. Here, in a case ofthe example in FIG. 7C, the touch-to-touch distance d1 is greater thanthe determination distance D1, and thus the touch panel controller 22provides different IDs to the two touch positions P1 a and P2 a asillustrated in FIG. 7B. For example, “ID1” and “ID2” are provided to thetwo touch positions P1 a and P2 a, respectively. Then, the touchcoordinate report includes the touch positions provided with the IDs.

The host controller 23 controls the in-cell touch panel device 100 byexecuting the program 24 a stored in the storage unit 24 illustrated inFIG. 1 . Further, the host controller 23 transmits a broadcast signal ora display signal acquired from a storage medium or a video playbackdevice (not illustrated) to the timing controller 21. The display signalincludes information about a magnitude of the refresh rate F(information indicating whether the refresh rate F is F1 or F2).

Further, the host controller 23 determines the refresh rate F. In thepresent embodiment, the host controller 23 changes the refresh rate Fbetween F1 and F2 (second rate) lower than F1. For example, the hostcontroller 23 sets the refresh rate F of the in-cell touch panel 1 toF1. Then, the host controller 23 changes the refresh rate F of thein-cell touch panel 1 from F1 to F2 lower than F1 when a touch by apointer is not detected in the in-cell touch panel 1 for a predeterminedperiod (for example, for several minutes). For example, when the refreshrate F is set to F2, as illustrated in FIG. 5 , a pause period in whichboth of the period DP (period for displaying an image) and the period TP(period for detecting a touch position) are not provided is added to adrive period in which the period DP and the period TP are provided. Inthis way, one frame period is extended. The example in FIG. 5illustrates the example in which one frame period becomes twiceaccordingly when the refresh rate F is changed from F1 to F2, but oneframe period may have a length other than twice. Note that a state wherethe refresh rate F is F2 is the sleep state where power consumption isreduced, and the power consumption is reduced by providing the pauseperiod in the in-cell touch panel device 100.

Further, F1 is a value of the highest refresh rate that the in-celltouch panel 1 can take. As illustrated in FIG. 5 , the pause period isnot provided within one frame period. When the refresh rate F is F1, acycle in which the touch coordinate report is output according to F1 isalways t1. Further, when the refresh rate F is F2, a cycle in which thetouch coordinate report is output is t1 within the drive period, and,when a cycle in which the touch coordinate report is output enters thepause period, the cycle in which the touch coordinate report is outputis t2 (see FIG. 8A) longer than t1. In other words, when the refreshrate F is F2, the control circuit 20 causes the in-cell touch panel 1 toperform detection of a touch position in the cycle t2 being a cyclelonger than the cycle t1, at the end within one frame period.

FIG. 8A is a diagram illustrating a waveform of the signal INT and awaveform of a rate change notification signal RS when the refresh rate Fis changed from F2 to F1. FIG. 8B is a diagram illustrating an exampleof display of the in-cell touch panel 1 when the refresh rate F ischanged from F2 to F1. As illustrated in FIG. 8A, when the refresh rateF is F2, the host controller 23 changes the refresh rate F of thein-cell touch panel 1 from F2 to F1 in response to detection of a touchby a pointer on the in-cell touch panel 1. In this way, the refresh rateF can be increased to F1 as necessary while reducing power consumptionby setting the refresh rate F to F2. Note that after the frame period ata time point of the touch ends, the refresh rate is changed from F2 toF1 from a next frame period.

Here, the program 24 a illustrated in FIG. 1 includes, for example,drawing software (paint software). The host controller 23 makes a pointcorresponding to a touch position be displayed on the in-cell touchpanel 1. Here, as illustrated in FIG. 6C, by the host controller 23, aline connecting points corresponding to the touch positions P1 and P2provided with the same ID (for example, “ID1”) is made to be displayedon the in-cell touch panel 1. Further, as illustrated in FIG. 7C, thehost controller 23 does not allow display of a line connecting pointscorresponding to the plurality of touch positions P1 a and P2 a providedwith the different IDs.

FIG. 9A is a diagram for describing an operation of an in-cell touchpanel device 200 according to a comparative example. FIG. 9B is adiagram illustrating an example displayed on an in-cell touch panel 201of the in-cell touch panel device 200 according to the comparativeexample. FIG. 9A illustrates an example in which a touch by a pointer isdetected when the refresh rate F is F2, and the refresh rate F ischanged from F2 to F1.

In the in-cell touch panel device 200 according to the comparativeexample, regardless of the magnitude of the refresh rate F, thetouch-to-touch distance d1 being a distance between two successive touchpositions is compared with the determination distance D1. In this case,as illustrated in FIG. 9A, when the refresh rate F is switched from F2to F1, a period in which the touch coordinate report is not acquired isextended to t2. Thus, even when the in-cell touch panel 201 issuccessively touched by a pointer, the touch-to-touch distance d1between a last touch position in a period in which the refresh rate F isF2 and a first touch position in a period in which the refresh rate F isF1 increases as illustrated in FIG. 9B. As a result, the last touchposition in the period in which the refresh rate F is F2 is providedwith a different ID (for example, “ID2”) from that of the first touchposition in a period in which the refresh rate F is F1. In this way, inthe in-cell touch panel device 200 according to the comparative example,the touch position successively touched by the pointer is mistakenlyprovided with the different ID. As a result, as illustrated in FIG. 9B,a line is broken and displayed in display on the in-cell touch panel 201by the paint software.

In contrast, as illustrated in FIGS. 8A and 8B, in the in-cell touchpanel device 100 according to the present embodiment, when atouch-to-touch distance d2 between a touch position P3 detected last inthe period in which the refresh rate F is F2 and a touch position P4detected first since the period in which the refresh rate F is F1 startsis equal to or less than a determination distance D2 greater than thedetermination distance D1, the same ID is provided to the touchpositions P3 and P4. Further, when the touch-to-touch distance d2 isgreater than the determination distance D2, different IDs are providedto the touch positions P3 and P4. In this way, even when thetouch-to-touch distance d2 is greater than the determination distanceD1, whether the same ID needs to be provided to the touch positions P3and P4 is appropriately determined based on the determination distanceD2. As a result, as illustrated in FIG. 8B, when the touch-to-touchdistance d2 is equal to or less than the determination distance D2, aline connecting the touch positions P3 and P4 is displayed in display onthe in-cell touch panel 1 by the paint software.

Specifically, the timing controller 21 detects whether the refresh rateF is F1 or F2 from the display signal received from the host controller23. Then, in response to the change of the detected refresh rate F fromF2 to F1, the timing controller 21 transmits the rate changenotification signal RS indicating the change of the refresh rate F tothe touch panel controller 22 as illustrated in FIG. 8A. “Transmittingthe rate change notification signal RS” indicates a change in level ofthe rate change notification signal RS from “Low” to “High”, forexample. According to the configuration, even when the host controller23 outside the control circuit 20 has a function of changing the refreshrate F, the control circuit 20 can detect a change of the refresh rateF. Further, the touch panel controller 22 changes the determinationdistance from D1 to D2 in response to reception of the rate changenotification signal RS (change to “High”), and returns the determinationdistance to D1 after a determination of the touch-to-touch distance d2based on the determination distance D2 is performed.

Here, as illustrated in FIG. 8A, when the refresh rate F is F2, the hostcontroller 23 changes the refresh rate F of the in-cell touch panel 1 toF1 from a frame after a frame in which a touch by a pointer on thein-cell touch panel 1 is detected. In this way, in the presentembodiment, when a touch is performed in a state where the refresh rateF is F2, the pause period occurs only once after the touch. As a result,as described above, by setting the determination distance to D2 only indetermination of the touch-to-touch distance d2, the touch positions P3and P4 can be associated with each other (no line displayed on thein-cell touch panel 1 is broken).

Note that, in the disclosure, the refresh rate F may be changed to F1from a frame later than a frame after a frame in which a touch isdetected. Even in this case, the timing controller 21 continues totransmit the rate change notification signal RS from a time point atwhich the touch is detected until the refresh rate F becomes F1. Thus,even when a frame in which the refresh rate F is F2 is repeated and thepause period occurs twice or more, the determination distance is set toD2, based on the rate change notification signal RS, and thus successivetouches can be appropriately detected (no line displayed on the in-celltouch panel 1 is broken).

Further, in a case where the refresh rate F is F1, when thedetermination distance is always set to D2, a determination distance isgreater than D1 optimal as the determination distance of the successivetouch-to-touch distance d1. In this case, for example, touches by twopointers illustrated in FIGS. 7A to 7C may be mistakenly detected assuccessive touches (a line may be mistakenly connected). In contrast, inthe present embodiment, after determination of the touch-to-touchdistance d2 by the determination distance D2 is performed once, thedetermination distance is returned to the optimal D1, and thus a falsedetermination described above can be prevented.

Method for Controlling In-Cell Touch Panel According to PresentEmbodiment

Next, with reference to FIG. 10 , a method for controlling the in-celltouch panel 1 according to the present embodiment will be described.FIG. 10 is a flowchart for describing control processing of the controlcircuit 20 and the host controller 23 according to the presentembodiment.

As illustrated in FIG. 10 , in step S1, the touch panel controller 22sets, to D1, a determination distance for determining whether the sameID is provided to touch positions having the touch-to-touch distance d1.

In step S2, control when the refresh rate F is F1 is performed. Forexample, as illustrated in FIG. 5 , the period DP for display of animage and the period TP for detection of a touch position arealternately performed within one frame period in a time division manner.Further, detection of a touch position is performed in each cycle t1.Then, as illustrated in FIGS. 6A to 6C, when the touch-to-touch distanced1 between the successively detected touch positions P1 and P2 is equalto or less than the determination distance D1, the same ID is providedto the touch positions P1 and P2. In this way, the touch positions P1and P2 are associated with each other. Further, as illustrated in FIGS.7A to 7C, when the touch-to-touch distance d1 between the successivelydetected touch positions P1 a and P2 a is greater than the determinationdistance D1, different IDs are provided to the touch positions P1 a andP2 a.

In step S3, whether the refresh rate F is changed from F1 to F2 isdetermined. In the present embodiment, whether the refresh rate F ischanged from F1 to F2 is determined based on a signal transmitted fromthe host controller 23 to the control circuit 20. When the refresh rateF is changed from F1 to F2, the processing proceeds to step S4, and,when the refresh rate F is not changed from F1 to F2, the processingreturns to step S2.

In step S4, control when the refresh rate F is F2 is performed. Forexample, as illustrated in FIG. 5 , the drive period in which the periodDP for display of an image and the period TP for detection of a touchposition are alternately performed in a time division manner and thepause period in which neither display of an image nor detection of atouch position is performed are provided within one frame period.

In step S5, processing of changing the refresh rate F from F2 to F1 bythe host controller 23 starts. For example, step S5 is performed inresponse to detection of a touch by a pointer. Further, in this step, achange of the refresh rate F from F2 to F1 is detected by the timingcontroller 21.

In step S6, the rate change notification signal RS (High state) istransmitted from the timing controller 21 to the touch panel controller22. Then, in this step, the determination distance is set to D2 by thetouch panel controller 22. Further, when the step is performed (duringstep S6 or a period before or after step S6), the change of the refreshrate F from F2 to F1 by the host controller 23 is completed.

Then, in step S7, predetermined waiting time is provided. The processingproceeds to next step S8 after the predetermined waiting time elapses.In this way, a first touch position since the refresh rate F becomes F1can be reliably acquired. Then, as illustrated in FIGS. 8A and 8B, whenthe touch-to-touch distance d2 between the touch position P3 detectedlast in the period in which the refresh rate F is F2 and the touchposition P4 detected first in the period in which the refresh rate F isF1 is equal to or less than the determination distance D2, the same IDis provided to the touch positions P3 and P4. As a result, the touchpositions P3 and P4 are associated with each other. Further, when thetouch-to-touch distance d2 is greater than the determination distanceD2, different IDs are provided to the touch positions P3 and P4.According to the control method described above, even when the refreshrate F is changed from F2 to F1, successive touches before and after thechange can be appropriately detected.

In step S8, the rate change notification signal RS is stopped (changedto a Low state). Accordingly, the determination distance is set to D1(returned to D1) by the touch panel controller 22. Further,subsequently, the processing returns to step S2.

Modifications and the Like

The above-described embodiments are merely examples for carrying out thedisclosure. Accordingly, the disclosure is not limited to theembodiments described above and can be implemented by modifying theembodiments described above as appropriate without departing from thescope of the disclosure.

(1) The embodiment described above exemplifies the example in which thetouch panel controller 22 changes the determination distance from D1 toD2 in response to reception of the rate change notification signal RS,but the disclosure is not limited thereto. For example, as in an in-celltouch panel device 300 according to a modified example illustrated inFIG. 11 , a touch panel controller may be configured to change thedetermination distance from D1 to D2 by comparing, with a determinationperiod ta1, a length of a period from a time point at which a previoustouch coordinate report is output to a time point at which a currenttouch coordinate report is output.

Specifically, when the length of the period from the time point at whichthe previous touch coordinate report is output to the time point atwhich the current touch coordinate report is output is t11 and is equalto or less than the determination period ta1, the touch panel controlleraccording to the modified example sets the determination distance to D1.When the length of the period from the time point at which the previoustouch coordinate report is output to the time point at which the currenttouch coordinate report is output is t12 and is greater than thedetermination period ta1, the touch panel controller sets thedetermination distance to D2.

(2) The embodiment described above exemplifies the example during theoperation of the paint software, but the disclosure is not limitedthereto. The contents can also be applied to the disclosure duringexecution of software other than the paint software, for example, when agesture action is recognized.

(3) The embodiment described above exemplifies the example in which therate change notification signal RS is formed as a signal indicatingeither “High” or “Low”, but the disclosure is not limited thereto. Forexample, the rate change notification signal RS may be formed of acommunication signal (a signal by serial communication using an I²C busor an SPI bus) transmitted from the timing controller 21 to the touchpanel controller 22. Further, the touch panel controller 22 may detect,as the rate change notification signal RS, a change in cycle of a pulsesignal transmitted to the touch panel controller 22 normally in aregular cycle.

(4) The embodiment described above exemplifies the example in which therefresh rate F is changed between two rates of F1 and F2, but thedisclosure is not limited thereto. For example, the refresh rate F maybe changed between three or more rates. In this case, a determinationdistance may be changed so as to be increased when the refresh rate F ischanged from a low rate to a high rate.

(5) The embodiment described above exemplifies the example in which thetouch positions P1 and P2, or the touch positions P3 and P4 areassociated with each other by being provided with the same ID, but thedisclosure is not limited thereto. For example, the touch panelcontroller 22 may generate information indicating that the touchpositions P1 and P2 are associated with each other (or the touchpositions P3 and P4 are associated with each other).

The in-cell touch panel device and the method for controlling an in-celltouch panel described above can be described as follows.

An in-cell touch panel device according to a first configurationincludes: an in-cell touch panel configured to perform display of animage and detection of a touch position in a time division manner; and acontrol circuit configured to control the in-cell touch panel, in whichthe control circuit is configured to change a refresh rate of thein-cell touch panel between a first rate and a second rate lower thanthe first rate, and the control circuit is further configured to causethe in-cell touch panel to perform detection of a touch position in afirst cycle when the refresh rate is the first rate, cause the in-celltouch panel to perform detection of a touch position in a second cyclebeing a cycle longer than the first cycle at the end at least within oneframe period, when the refresh rate is the second rate, associate afirst touch position and a second touch position with each other when atouch-to-touch distance between the first touch position and the secondtouch position is equal to or less than a first determination distance,the first touch position and the second touch position beingsuccessively detected in a period in which the in-cell touch panel iscaused to perform detection of a touch position in the first cycle, andassociate a third touch position and a fourth touch position with eachother when a touch-to-touch distance between the third touch positionand the fourth touch position is equal to or less than a seconddetermination distance greater than the first determination distance,the third touch position being detected last in a period in which therefresh rate is the second rate and the fourth touch position beingdetected first since a period in which the refresh rate is the firstrate starts, when the refresh rate is changed from the second rate tothe first rate (first configuration).

According to the first configuration, even when the refresh rate ischanged from the second rate to the first rate, and a period from a timepoint at which the third touch position before the change is detected toa time point at which the fourth touch position is detected is extended,whether the third touch position and the fourth touch position detectedbefore and after the change need to be associated with each other can bedetermined by using the second determination distance greater than thefirst determination distance. In this way, whether the third touchposition and the fourth touch position need to be associated with eachother can be appropriately determined as compared to a case where thefirst determination distance is used. As a result, even when the refreshrate is changed from the second rate to the first rate, successivetouches before and after the change can be appropriately detected.

In the first configuration, the control circuit may include anidentification information provision unit configured to provide the samepiece of identification information to the third touch position and thefourth touch position when a touch-to-touch distance between the thirdtouch position and the fourth touch position is equal to or less thanthe second determination distance, and provide different pieces ofidentification information to the third touch position and the fourthtouch position when a touch-to-touch distance between the third touchposition and the fourth touch position is greater than the seconddetermination distance (second configuration).

According to the second configuration, whether the third touch positionand the fourth touch position are associated with each other can beeasily determined by referring to the identification informationprovided to each of the third touch position and the fourth touchposition.

In the second configuration, the control circuit may further include arate change detection unit configured to detect a change of a refreshrate, and the rate change detection unit may be configured to transmit arate change signal indicating a change of the refresh rate to theidentification information provision unit in response to detection ofthe change of the refresh rate (third configuration).

According to the third configuration, the change of the refresh rate canbe detected even when a function of changing the refresh rate isprovided outside the control circuit.

In any one of the first to third configurations, the in-cell touch paneldevice may further include a refresh rate change unit configured tochange a refresh rate of the in-cell touch panel from the second rate tothe first rate in response to detection of a touch position performed bythe in-cell touch panel when the refresh rate is the second rate (fourthconfiguration).

According to the fourth configuration, the refresh rate can be increasedin response to a touch on the in-cell touch panel. As a result, therefresh rate can be increased as necessary while reducing powerconsumption by setting the refresh rate to the second rate.

A method for controlling an in-cell touch panel according to a fifthconfiguration is a method for controlling an in-cell touch panelconfigured to perform display of an image and detection of a touchposition in a time division manner, and includes: changing a refreshrate of the in-cell touch panel between a first rate and a second ratelower than the first rate; causing the in-cell touch panel to performdetection of a touch position in a first cycle when the refresh rate isthe first rate; causing the in-cell touch panel to perform detection ofa touch position in a second cycle being a cycle longer than the firstcycle at the end at least within one frame period, when the refresh rateis the second rate; associating a first touch position and a secondtouch position with each other when a touch-to-touch distance betweenthe first touch position and the second touch position is equal to orless than a first determination distance, the first touch position andthe second touch position being successively detected in a period inwhich the in-cell touch panel is caused to perform detection of a touchposition in the first cycle; and associating a third touch position anda fourth touch position with each other when a touch-to-touch distancebetween the third touch position and the fourth touch position is equalto or less than a second determination distance greater than the firstdetermination distance, the third touch position being detected last ina period in which the refresh rate is the second rate and the fourthtouch position being detected first since a period in which the refreshrate is the first rate starts, when the refresh rate is changed from thesecond rate to the first rate (fifth configuration).

According to the fifth configuration, similarly to the firstconfiguration described above, even when the refresh rate is changedfrom the second rate to the first rate, successive touches before andafter the change can be appropriately detected.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

1. An in-cell touch panel device comprising: an in-cell touch panelconfigured to perform display of an image and detection of a touchposition in a time division manner; and a control circuit configured tocontrol the in-cell touch panel, wherein the control circuit isconfigured to change a refresh rate of the in-cell touch panel between afirst rate and a second rate lower than the first rate, and the controlcircuit is further configured to cause the in-cell touch panel toperform detection of a touch position in a first cycle when the refreshrate is the first rate, cause the in-cell touch panel to performdetection of a touch position in a second cycle being a cycle longerthan the first cycle at the end at least within one frame period, whenthe refresh rate is the second rate, associate a first touch positionand a second touch position with each other when a touch-to-touchdistance between the first touch position and the second touch positionis equal to or less than a first determination distance, the first touchposition and the second touch position being successively detected in aperiod in which the in-cell touch panel is caused to perform detectionof a touch position in the first cycle, and associate a third touchposition and a fourth touch position with each other when atouch-to-touch distance between the third touch position and the fourthtouch position is equal to or less than a second determination distancegreater than the first determination distance, the third touch positionbeing detected last in a period in which the refresh rate is the secondrate and the fourth touch position being detected first since a periodin which the refresh rate is the first rate starts, when the refreshrate is changed from the second rate to the first rate.
 2. The in-celltouch panel device according to claim 1, wherein the control circuitincludes an identification information provision unit configured toprovide the same piece of identification information to the third touchposition and the fourth touch position when a touch-to-touch distancebetween the third touch position and the fourth touch position is equalto or less than the second determination distance, and provide differentpieces of identification information to the third touch position and thefourth touch position when a touch-to-touch distance between the thirdtouch position and the fourth touch position is greater than the seconddetermination distance.
 3. The in-cell touch panel device according toclaim 2, wherein the control circuit further includes a rate changedetection unit configured to detect a change of a refresh rate, and therate change detection unit is configured to transmit a rate changesignal indicating a change of the refresh rate to the identificationinformation provision unit in response to detection of the change of therefresh rate.
 4. The in-cell touch panel device according to claim 1,further comprising a refresh rate change unit configured to change arefresh rate of the in-cell touch panel from the second rate to thefirst rate in response to detection of a touch position being performedby the in-cell touch panel when the refresh rate is the second rate. 5.A method for controlling an in-cell touch panel configured to performdisplay of an image and detection of a touch position in a time divisionmanner, the method comprising: changing a refresh rate of the in-celltouch panel between a first rate and a second rate lower than the firstrate; causing the in-cell touch panel to perform detection of a touchposition in a first cycle when the refresh rate is the first rate;causing the in-cell touch panel to perform detection of a touch positionin a second cycle being a cycle longer than the first cycle at the endat least within one frame period, when the refresh rate is the secondrate; associating a first touch position and a second touch positionwith each other when a touch-to-touch distance between the first touchposition and the second touch position is equal to or less than a firstdetermination distance, the first touch position and the second touchposition being successively detected in a period in which the in-celltouch panel is caused to perform detection of a touch position in thefirst cycle; and associating a third touch position and a fourth touchposition with each other when a touch-to-touch distance between thethird touch position and the fourth touch position is equal to or lessthan a second determination distance greater than the firstdetermination distance, the third touch position being detected last ina period in which the refresh rate is the second rate and the fourthtouch position being detected first since a period in which the refreshrate is the first rate starts, when the refresh rate is changed from thesecond rate to the first rate.